Multiple-clutch device

Abstract

A multiple-clutch device, possibly a double-clutch device, for arranging in a drivetrain of a motor vehicle between a drive unit and a transmission. the clutch device has a first clutch arrangement associated with a first transmission input shaft of the transmission and a second clutch arrangement associated with a second transmission input shaft of the transmission for transmitting torque between the drive unit and the transmission. The clutch arrangements are constructed as plate clutch arrangements, one of which has a greater effective friction radius than the other. Steps are taken to make the torque-transmitting capacity of the plate clutch arrangement with the smaller effective friction radius at least approximately equal to the torque-transmitting capacity of the plate clutch arrangement with the larger effective friction radius with respect to a reference input quantity, possibly a reference actuation pressure, which determines the strength of the frictional engagement of the plates and which is the same for both clutch arrangements.

We claim:  
     
       1. A multiple-clutch device, arrangable in a drivetrain of a motor vehicle between a drive unit and a transmission, the clutch device comprising; a first clutch arrangement associated with a first transmission input shaft of the transmission; and a second clutch arrangement associated with a second transmission input shaft of the transmission for transmitting torque between the drive unit and the transmission, the clutch arrangements being constructed as plate clutch arrangements, one of the plate clutch arrangements having a greater effective friction radius than the other, the plate clutch arrangement with the smaller effective friction radius having a torque-transmitting capacity at least substantially equal to a torque-transmitting capacity of the plate clutch arrangement with the larger effective friction radius with respect to a reference input quantity which determines a strength of frictional engagement of plates of the arrangements and which is equal for both clutch arrangements, each of the clutch arrangements having an actuating piston defining a pressure chamber for actuation of the clutch arrangement by means of a hydraulic pressure medium, the actuating piston of the plate clutch arrangement with the smaller effective friction radius having a pressure application surface exposed to the hydraulic pressure medium at least for actuating the clutch arrangement, the effective pressure application surface being larger than a pressure application surface of the actuating piston of the plate clutch arrangement with the larger effective friction radius, whereby each of the pistons can be acted upon by different axial pressing forces. 
     
     
       2. A clutch device according to  claim 1 , wherein the plate clutch arrangement with the larger effective friction radius is operative as a starting clutch.